Circulating PMN were identified by injecting mice with intravenous fluorochrome conjugated anti-CD45 antibody prior to tissue harvesting. Interstitial PMN were identified as Ly6G+ CD45-, while circulating PMN were identified as Ly6G+ CD45+. Alveolar cells, which are not in the circulation, were used to verify that the intravenous anti-CD45 antibody was not leaking from the blood into the tissue. Representative histogram is shown on the left for vascular and tissue pulmonary neutrophils. Bar graph displaying the percentage of CD45- interstitial neutrophils is shown on the right. Each data point represents an individual experiment (n). Bars represent s.e.m.